The present invention relates generally to fluid inspection systems and particularly to a flow cell device for observing a fluid passing through it. The present invention also relates to a method for observing a fluid in a flow cell.
Various devices have been used for inspecting a fluid inside of process vessels, engine, pipes, hoses, or other fluid-containing receptacles. For example, it is known to use a viewing port on the side of a vessel or pipeline to view its interior. Many such viewing ports employ a glass disk bolted to the side of the vessel or pipe in various configurations. Structurally superior examples of a viewing unit are disclosed, for example, in U.S. Pat. Nos. 4,809,862 and 6,359,742, which are both incorporated by reference herein. Other types of window viewing units are described, for example, in U.S. Pat. Nos. 2,744,487, 3,299,851, 3,837,226 and 4,245,566. For certain industrial processes, it is desired to use instrumentation, such as imaging and measuring systems in conjunction with a viewing device to provide remote analysis of the process conditions. For example, U.S. Pat. No. 4,977,418 describes a camera viewing device that provides remote viewing of a vessel interior.
Many industrial processes involve fluids that contain particles suspended within the fluids. It is desired, for many of these processes, to observe those fluids in order to determined characteristics of the fluids, such as, for example, the size, shape, or color of the particles. Known devices for observing process fluids have not been adequate in providing a safe or accurate solution for observing process fluids. In addition, many of these known devices do not provide precise conditions for presenting the fluid to for optimal viewing.
Known devices have included fixed aperture cells, or cells having an aperture between two opposing plates in which the aperture can only be adjusted offline. Typically, these cells consist of two thin glass plates glued together with a gasket therebetween for forming an aperture. In some cases, a bolted assembly of metal plates may be used to retain the thin glass flow cells. Such a thin glass plate construction, typical of known flow cells, is subject to breakage or leakage. The thickness of the aperture is either unchangeable or can only he changed offline (i.e. it must be first be disconnected from the fluid flow), requiring considerable time and effort. The flow and analysis of the process fluid must cease during that time. The aperture is typically changed by disassembling the flow cell and replacing the gasket with another gasket of a different thickness. Changing the aperture in these cells not only wastes time, but the selection of aperture thickness is limited by the sizes of the available gaskets.
U.S. Pat. No. 6,104,483 (the xe2x80x9c""483 patentxe2x80x9d) describes a fluid inspection system that includes an optical flow cell for use with an imaging system. The optical flow cell described in the ""483 patent includes a housing and a pair of two opposing optical plates through which a sample fluid material flows. This optical flow cell again has the disadvantage that the gap between the opposing optical plates is not adjustable and is suitable only for observing fluid samples, as in a laboratory environment, not for on-line use in an ongoing industrial process.
Precise aperture thickness adjustment is desired for improved viewing and measuring of different characteristics of the same or different process fluids. Changing the aperture thickness using different sized gaskets is time consuming, inexact and often not reliably repeatable. The optimal aperture for observing a fluid will vary depending on which characteristics of the fluid are desired to be observed at any given time. The optimal aperture will also depend on properties of the fluid and of any suspended particles. Characteristics that may be observed include, among others, the turbidity and color of the fluid, as well as the size, shape, density, opaqueness, and color of the particles.
It is also desired to provide a system of observing a fluid with improved ruggedness, durability, and the capability to handle extreme environments, such as high or low pressures and/or high or low temperatures.
The present invention provides a flow cell device for observing a fluid including a housing defining an inlet and an outlet and a viewing assembly coupled to the housing. The viewing assembly includes a first viewing member adjacent to an aperture that is in fluid communication with the inlet and the outlet. The first viewing member is configured to enable a viewing of the fluid in the aperture and is adjustable with respect to the housing so that a thickness of the aperture is variable.
The viewing assembly may also include a second viewing member disposed opposite the first viewing member and the aperture defined between the first and second viewing members. The housing may include a first housing half and a first sealing element may be disposed between the first housing half and the viewing assembly. The viewing assembly may include a first adapter member disposed between the first viewing member and the housing. The viewing assembly may include a second adapter disposed between the second viewing member and the housing.
At least one of the first and second viewing members may be configured to enable an illumination of the fluid in the aperture. Thus, in one case, both viewing and illumination can be performed through the first viewing member. In another case, viewing and illumination can be performed from opposite sides of the aperture.
At least one of the first and second viewing members may include a viewing port and the other of first and second viewing members may include an illumination port. The viewing port and/or illumination port may include a transparent viewing window disposed therein. The transparent viewing window is preferably glass and is fused to a metal portion of one of the first and second viewing members.
The flow cell device may also include a light source coupled to one of the first and second viewing members, which may include a fiber optic bundle, which may be configured to form a ring arrangement, a point arrangement, or a broadly dispersed arrangement at a position adjacent to one of the first and second viewing members. A camera may be coupled to the viewing port of the flow cell device. The camera may also include a light source to provide illumination to the fluid, for those situations in which direct lighting of the fluid from the same direction as the camera provides optimal imaging. In addition, a flow path of the fluid preferably includes a rectangular cross-section when the fluid is in the aperture.
An inlet reservoir in fluid communication with the inlet, may also be included in the flow cell. The inlet reservoir preferably has a greater volume than a volume of the fluid in the aperture. The inlet may be narrower than the thickness of the aperture. The viewing assembly is preferably suitable for containing the fluid at a high pressure, for example a pressure up to 6000 p.s.i. A second inlet and or a second outlet in fluid communication with the aperture may be defined in the housing.
The present invention also provides a method for observing a fluid in a flow cell. The method includes passing the fluid through an adjustable aperture defined, on one side, by a first viewing member that is moveable so that a thickness of the aperture is adjustable. The method also includes viewing the fluid through the first viewing member as the fluid passes through the aperture.
A second side of the aperture may be defined by a second viewing member so that the fluid passes through the two viewing members. The method may also include the step of moving the first viewing member so as to adjust the thickness of the aperture.
The viewing may be performed using a camera coupled to the first or second viewing member. The method may also include illuminating the fluid through either one of the first and second viewing members. The illuminating may be performed using a fiber optic bundle, which may be arranged in a ring-shape, coupled to the first or second viewing member.